Dual action of anti-sporozoite antibodies in vitro

With the use of a double staining technique that permits localization of the sporozoite during the process of entering a host cell, we studied the biologic effects of three mAb directed against determinants contained in the circumsporozoite of Plasmodium yoelii. These mAb, which included one IgM and two IgG3, were studied in primary cultures of rodent hepatocytes inoculated with sporozoites of P. yoelii. These results confirm previous reports of the extended action of antibodies on Plasmodium falciparum after entering hepatocytes by producing a strong intrahepatocyte inhibitory effect in addition to the inhibitory effect on sporozoite entry. As with P. falciparum the intracellular effects on P. yoelii liver stages are only observed when the antibodies are present at the time the sporozoite enters the cell. While carrying out experiments on this phenomenon, it was discovered that, at lowered antibody concentrations, an increase in number of maturing liver schizonts occurs, with the increase or enhancement of infection reaching up to 150% of that of controls. It was also observed that there was an inverse relationship between the antibody concentration that was inhibitory and that which enhanced parasite infectivity.     

Detection of a rare allele with the pMP6d-9/MspI RFLP near the cystic fibrosis locus

Summary We report a rare allele detected using pMP6d-9, a probe very closely linked to cystic fibrosis (CF), on digestion with MspI. This allele has been found in normal and CF chromosomes, and therefore cannot be related to the mutation causing the disease.     

Ferritin H gene polymorphism in idiopathic hemochromatosis

Summary We have analysed karyotypes and DNA from three patients with aniridia (congenital absence of irises) and Wilms' tumour. All three had constitutional deletions from the short arm of chromosome 11. The minimum region of overlap of the deletion involves a small region of band 11p13 presumed to contain the genetic loci responsible for both phenotypic abnormalities. Using cells from these patients, somatic cell hybrids with transformed mouse cells have been prepared. Individual subclones retaining either the deletion-11 chromosome or the normal chromosome 11, in addition to a variety of other human chromosomes, have been identified. The relative position of these breakpoints have been determined and the panel of hybrids has been used to map randomly-isolated 11p13 DNA sequences. The characterisation of these deletions has provided a useful panel of hybrids for random mapping strategies designed to identify the Wilms' and aniridia genes.     

Impaired local natural killer cell activity in human colorectal carcinomas

Summary The present study was undertaken to study natural killer (NK) cell activity in patients with colorectal cancer at peripheral and local levels. Mononuclear cells were isolated from uninvolved colorectal mucosa, tumor tissue and peripheral blood, and tested against the colon carcinoma cell line CaCo-2 and the erythroleukemia cell line K-562. Peripheral blood NK cell activity from the patients showed similar levels compared with healthy controls, whereas, mononuclear cells of tumor tissue were found to have a significantly decreased NK cell activity compared to the normal intestinal mucosa (P<0.01). No relation was found between the NK cell activity and the advancement of the disease according to the Duke's stage. Interferon- (IFN-) stimulated the NK cell activity of the mononuclear cells from blood, mucosa and tumor. However, the increase of NK cell activity after IFN- stimulation was lower in the tumor compared to the mucosa (P<0.02). The lectin, phytohaemagglutinin, increased the cytotoxicity of mononuclear cells from blood, mucosa and tumor to a similar level. These results suggest that patients with colorectal tumors exhibit a normal NK cell activity in peripheral blood and intestinal mucosa; however, a diminished NK cell activity exists at the tumor level. Although mononuclear cells isolated from the tumor have a normal response to lectin stimulation they show hyporesponsiveness to IFN- stimulation with regard to their NK cell activity.     

Distribution of radiolabelled monoclonal antibody Po66 after intravenous injection into nude mice bearing human lung cancer grafts

Monoclonal antibody Po66, produced by immunization against a patient's lung squamous cell carcinoma was found suitable for the scintigraphic detection of human tumours. Surprisingly, the cellular antigen recognized by Po66 was abundant in the cytoplasm of tumour cells but could not be detected on the surface membrane. In the present work the biodistribution of radiolabelled Po66 and of an unrelated immunoglobulin were studied comparatively after intravenous injection into nude mice bearing lung squamous cell carcinoma grafts. Radioactivity distribution among mouse organs and tumour was analysed by gamma counting and autohistoradiography. After injection, radiolabelled Po66 decreased rapidly from the blood in tumour-bearing animals whereas, in controls, it remained at a level comparable to that of the unrelated immunoglobulin. The antibody seemed slowly trapped by the tumour and, 12 days after its injection, distribution ratios between tumour and mouse organs reached values of 20-30 as against 1 in animals injected with the non-specific immunoglobulin. Autohistoradiographic investigations in the tumour confirmed the slow diffusion rate of the antibody, which remained in the vascular spaces up to the 24th hour after injection and diffused afterwards throughout the clusters of tumor cells. Furthermore, radioactivity was detected in cells which, unexpectedly, seemed morphologically unaltered. These cells, the viability of which remains to be determined, were predominant in the central area of the tumours. The results presented constitute new evidence of the ability of an in vivo injected monoclonal antibody to reach a cytoplasmic target inside non-necrotic cells and suggest that the cells permeable to the antibody might be in defective nutritional conditions.     

Detection of 1q polysomy in interphase nuclei of human solid tumors with a biotinylated probe

Summary A biotinylated probe (L23-21) specific for the 1q12 band of human karyotype was used to detect the 1q segment in interphase nuclei of breast and colon carcinomas. This probe was selected because trisomy or polysomy 1q is the most frequent chromosomal change observed in solid tumors. This method enables cancerous cells, including near-diploid ones carrying an unbalanced rearrangement of 1q, to be easily identified.     

Large phase-shifts of circadian rhythms caused by induced running in a re-entrainment paradigm: The role of pulse duration and light

Summary Bouts of induced wheel-running, 3 h long, accelerate the rate of re-entrainment of hamsters' activity rhythms to light-dark (LD) cycles that have been phase-advanced by 8 h (Mrosovsky and Salmon 1987). The bouts of running are given early in the first night of the new LD cycle, and by the second night the phase advance in activity onset already averages 7 h. Such large shifts contrast with the mean phase advance of <1 h at the peak of the phase response curve when hamsters in constant darkness (DD) experience 2-h pulses of induced activity (Reebs and Mrosovsky 1989). The present paper investigates pulse duration and light as possible causes for the discrepancy in shift amplitude between these two studies. In a first experiment, pulses of induced wheel-running 1 h, 3 h, or 5 h long were given at circadian times (CT) 6 and 22-2 to hamsters free-running in DD. Pulses given at CT 6 caused phase-advances of up to 2.8 h, whereas pulses at CT 22-2 resulted in delays of up to 1.0 h. Shifts after 3-h and 5-h pulses did not differ, but were larger than after 1-h pulses, and larger than after the 2-h pulses given in DD by Reebs and Mrosovsky (1989). Thus 3 h appears to be the minimum pulse duration necessary to obtain maximum phase-shifting effects. In a second experiment, the re-entrainment design of Mrosovsky and Salmon (1987) was repeated with the light portion of the shifted LD cycle eliminated. Hamsters exercised for 3 h phase-advanced 2.9 h on average (excluding 2 animals who ran poorly). When the same hamsters were exposed 7 days later to a 14-h light pulse starting 5 h after their activity onset, they advanced by an average of 3.3 h. Adding the average values for activity-induced shifts and light-induced shifts gives a total of about 6 h. Possible synergism between the effects of induced activity and those of light may account for the remaining small difference between this total and the 7-h advances previously reported.Abbreviations CT circadian time - DD constant darkness - LD light-dark - PRC phase response curve - free-running period of rhythm     

Chromosomal localization of ARSB,the gene for human N-acetylgalactosamine-4-sulphatase

Summary A deficiency of N-acetylgalactosamine-4-sulphatase (G4S, gene symbol ARSB), results in the accumulation of undegraded substrate and the lysosomal storage disorder, Maroteaux-Lamy syndrome (mucopolysaccharidosis type VI). In situ hybridization using an ³H-labelled human G4S genomic DNA fragment to human metaphase chromosomes localized ARSB to chromosome 5q13–5q14. This location is consistent with, an refines, previous chromosomal assignments based on the expression of human G4S in somatic cell hybrids.     

Entrainment and phase shifting of the circadian rhythm of cell division by light in cultures of the achlorophyllous ZC mutant ofEuglena gracilis

The photosynthesis-deficient ZC mutant ofEuglena gracilis Klebs (strain Z) was cultured at 16°C on an aerated, magnetically stirred, mineral medium containing 0.1% ethanol (pH 7.0). Cell division could be entrained by a 12: 12 light: dark cycle (LD: 12, 12) or even by a one-pulse skeleton photoperiod (LD: 1,23) The rhythm free-ran in DD for at least 8 days with a circadian period (=25.5 h) in populations that had been previously entrained by LD. The freerunning rhythm could be phase-shifted by a single 1-h light pulse (3000 lx). The strong (Type 0) phase-response curve derived from the resetting effects of such signals given at different circadian times was similar to that for the photosynthetic wild-type strain. These results demonstrate that the presence of a functional chloroplast compartment is not necessary for the circadian clock to function inEuglena and suggest that phase resetting of the circadian clock by light occurs via a similar pathway in both photosynthetic and non-photosynthetic cell types.